Stereospecific analysis of triacylglycerols rich in long-chain polyunsaturated fatty acids

Lipids. 1996 Feb;31(2):207-15. doi: 10.1007/BF02522622.


Six oils of marine, algal, and microbial origin were analyzed for stereospecific distribution of component fatty acids. The general procedure involved preparation of sn-1,2-(2,3)-diacylglycerols by partial deacylation with ethylmagnesium bromide or pancreatic lipase, separation of X-1,3- and sn-1,2(2,3)-diacylglycerols by borate thin-layer chromatography, resolution of the sn-1,2- and sn-2,3-enantiomers by chiral phase high-performance liquid chromatography following preparation of dinitrophenylurethane derivatives, and determination of the fatty acid composition by gas chromatography. Unexpected complications arose during a stereospecific analysis of triacylglycerols containing over 33% of either 20:4 or 22:6 fatty acids. The sn-1,2(2,3)-diacylglycerols made up of two long-chain polyunsaturated acids migrated with the X-1,3-diacylglycerols and required separate chiral phase resolution. Furthermore, the enzymatic method yielded sn-1,2(2,3)-diacylglycerols, overrepresenting the polyenoic species due to their relative resistance to lipolysis, but prolonged digestion yielded correct composition for the 2-monoacylglycerols. The final positional distribution of the fatty acids was established by pooling and normalizing the data from subfractions obtained by normal- and chiral-phase separation of diacylglycerols. The molecular species of X-1,3-, sn-1,2- and sn-2,3-diacylglycerol dinitrophenylurethanes were identified by chiral-phase liquid chromatography/mass spectrometry with electrospray ionization, which demonstrated a preferential association of the paired long-chain acids with the sn-1,2- and sn-2,3-diacylglycerol isomers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatography, Gas
  • Chromatography, High Pressure Liquid
  • Diglycerides / analysis
  • Eukaryota
  • Fatty Acids, Unsaturated / analysis*
  • Fish Oils / analysis
  • Glycerides / analysis
  • Mass Spectrometry
  • Oils / analysis*
  • Stereoisomerism
  • Triglycerides / analysis*


  • 1,2-diacylglycerol
  • Diglycerides
  • Fatty Acids, Unsaturated
  • Fish Oils
  • Glycerides
  • Oils
  • Triglycerides